Internal-combustion engine with variable compression ratio



y 1946. Due. PRINCE 2,401,l8 8

INTERNAL-COMBUSTION ENGINE WITH VARIABLE COMPRESSION RATIO Fil ed March 1, 1943 2 Sheets-Sheet 1 Inventor; David C.-Pr"i-'nc:e, b )Vamy) y his Attorney.

May "28, 1946. D. c. PRINCE 2,401,188

. INTERNAL-COMBUSTION ENGINE WITH VARIABLE COMPRESSIONRATIO Filed March 1, 1945 2 Sheets-Sheet 2 1 Fig.2;

- Inventor: Dgvid C.P-hince,

; His Attome Patented May 28, 1946 David 0. Prince, Schenectady, N. Y., assignor-to H General Electric Company, a corporation of.

Application March 1, 1943,"Serial No. 477,512 '2 Claims. (01. 123-48) Y The present invention relatesto internal combustion engines with variable compression ratio of the type having a pair orpairs of pistons with a common combustion chamber for each'pair and separate drive or crank shafts connected to the pistons of each'pair together with means'for adjusting the angular. relation of the drive or crank shafts. y

One object of my invention is to provide an improved construction and arrangement of the above type of combustion engines. Another object of my invention is toprovide an improved mechanism f orcontrolling engines with variable ratio compression whereby better efficiency and economy are obtained.

This is accomplished in accordance with myinvention by an arrangement including means for controlling the compression ratio i -response to load changes on'the engine to operate the engine at high compression ratio during starting and at low load and at low compression ratio whenthe engine is hot and carrying high load.

For a better understanding of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto in connection with the accompanying drawings. l

In the drawings Fig. 1 illustrates diagrammatically a; supercharged internal combustion engine of the solid fuel injection type such as a llliesel engine embodying'my' invention, Fig. 1a is an assembly view of certain parts of Fig. 1, and Fig.

2 illustrates a modification according to my invention. e

The arrangement comprises a cylinder ill with a pair of opposed pistons II, I! disposed therein and forming between them a common combustion and compression space l3 to which fuel is supplied by means including a, nozzle M. The left-hand portion of the cylinder Ill forms a from the cylinder. Thepistons ll, I2 are connected by rods I1 and 13 respectively, to separate stance by sprockets 2i and 22 secured to the shafts l9 and respectively and connected byia chain 23.

Fuel is forced through the aforementioned noze zle 'I4 bymeans of a. fuel pump 14 whichhas an inlet conduit 25 for connection to a sourceof fuel and a discharge conduit 26 connected to the nozzle l4. The pump is of the reciprocating type with a plungerfl biased outward-by a. spring 28 and actuated by means of e an actuating rod 29 from a cam 30 fastened to the drive shaft l9.

A wedge 3 I is interposed between the pump plunger 2'! and, the actuating rod 29 andmay be posisupply port l5 for compressed air and the righttioned by means including a bell crank 32 with a handle 33 to vary "the fuel supply. Inthe position shown the fuel sup ly is at a minimum and may be increased upon counterclockwise turning movement of the bell crank 32. l

Air under pressure is supplied to the cylinder In through the port I5 by means of a blower 34 having an inlet 35 for receiving air from the atmosphere and an outlet 36 connected to the port 15. The blower 34 is driven by'an'exhaust gas operated turbine 31 which has a nozzle box 38.

'An electric machine 4| is provided with its rotor secured to the shaft4ll and its stator connected by conductor 42 toapower line 43. Other electrica1 machines 44 and45 are mechanically connected to the drive shafts l9 and 20 respectively and electrically connected to the line 43. During operation compressed air for maintainingcombustion is supplied to'thecylinder ID from the blower 34,'the supply being controlled by movement of the piston I l. After combustion of the fuel supplied through the nozzle I4 burned gases are discharged through the port 10, the discharge being controlled by the piston [2. The exhaust gases are utilized to operate the turbine 31 for driving theblower 34, and also the maj chine 4! which latter during normal operation drive shafts l9 and 20 respectively. The com pression ratio in an arrangement of this kind depends on thephase relation between the pistons I l and I2, maximum compression ratio being obtained when the pistons are in synchronism, that j is, reach s'imultaneously'their inner dead-center positions. In order to maintain certain phase relationships between the pistons II, I 2 means are provided for interconnecting the shafts l9 and 20. This is accomplished ,in the present inacts as a generator supplying electric energyto the line 43. Likewise the machines 44 and 45 act normallyas generators for converting mechanical energy in.. the drive shafts I9. 20 into electrical energy and supplying it to the line 43. At low engine speed and during starting the machine 4| acts as a motorfedfrom the line 43 and aiding the turbine 31 to drive the blower 34.

During starting when theengine is cold and also at low engine speed a high compression ratio is necessary to assure ignition. At high engine speed and high'load'output itis desirable to reduce the compression ratio in the interest of best efficiency and economy. Also, lower compression ratio reduces the wear and tear on the engine. Finally, if the engineis supercharged at a low compression'ratio it can handle a great deal more air. Hence, more fuel can be burned, and the output can be materially increased without the drawback of maximum pressure ratio durin normal operation. This is accomplished inaccordance with my invention by the provision of means for automatically varying the angular relation between the shafts l9 and 20 in response to load change on the engine. To this end I provide a mechanism for turning the sprockets 2|, 22 in opposite directions in response to load changes on the engine. The mechanism diagrammatically shown in the drawings includes rollers 49, 50 engage the lower side of the lower portion of the chain 23. The sprockets2l, 22 as indicated by arrows rotate normally in clockwise direction and their angular relation is normally fixed by their connection through the chain 23.

reduce the compression ratio the dephasing is preferably in the direction to advance the re]- ative phase of the piston uncovering the exhaust Downward movement of the frame 46 tends to aid the clockwise rotation of the sprocket 2| and at the same time tends to retard or counteract the rotation of the sprocket 22,. Thus, by forcing the frame 46 downwardthe angular relation between the sprockets 2|, 22 and accordingly the pistons l2 may be changed to reduce the ratio of compression in the cylinder I0.

'Upon downward movement of the frame 46 ment of the sprocket 2| the piston II will reach its dead-center. position earlier. On the other hand, if piston I2 is also moved to the right,

that is, away from its dead-center position, it will reach such dead-center position later. Hence, if one piston reaches, the dead-center position earlier and the other one later, the phase angle between the pistons must increase and the compression or the compression ratio consequently must decrease.

Upward movement of the frame 46 likewise causes a change of the compression ratio except that in this case the sprocket 2| is retarded and the sprocket 22 is accelerated, causing a phase displacement of the pistons in a direction opposite of that accomplished upon downward movement of the frame 46. In one case the piston reaches its dead-center position first and in the.

other case the piston '|2 reaches its dead-center position first. According to my invention, the adjustment is made in one side of the condition for which the pistons arrive simultaneously at their upper dead-center. If the pistons do not arrive simultaneously the compression ratio is reduced regardless of which piston arrives at dead-center first. When the pistons are not perfectly synchronized the exhaust and intake ports are not simultaneously uncovered by their respective pistons. If the pistons are dephased to port. This permit high pressure gas to exhaust.

before the intake port is opened.

'In the arrangement shown in Fig. 1 vertical movement of the frame 46 is accomplished by means responsive to changes of the pressure in the cylinder [0. This means includes a cylinder 5| with a piston 52 biased upward by a compression spring 53 engaging at its upper end the piston 52 and at its lower end a fixed support 54. i The piston 52 has a stem, 55 secured to the frame 46. The lower portion of the frame is supported by another compression spring 56 engaging at its upper end the frame and at its lower end another fixed support 51. Downward movement of the frameis limited by a stop 58 cooperatively associated with a projection 59 secured to the frame 46. .The pressure chamber .sure variations durin each cycle of the engine.

During operation'increase of the mean pressure in the compression space I3 due to increase in load 'on the engine causes downward movement of the frame 46, thereby increasing the phase angle between the shafts l9 and 20 to reduce the compression ratio of the engine. Similarly, a decrease in compression effects upward movement ofthe piston 52 by action of the springs 53 and 56 to reduce the angular displacement of the shafts H), 20 and thereby to increase the compression ratio of the engine. The springs 53 and 56 are" preferably so proportioned that thecompression ratio will not be reduced until the explosion pressure in the engine exceeds a predeterrr'iined pressure required for ignition and maximum efficiency. Any higher pressure with In the position shown both pistons'are' its associated higher temperature would cause losses due to excessive radiation and disassociation of gases. The effect of disassociation is to prevent actual combustion from taking place during part of the power stroke and power that would otherwise be generated by complete combustion is therefore lost.

The arrangementof Fig. 2 comprises a cylinder 65 corresponding to the cylinder ID of Fig. 1 and including two opposed pistons 66, 61 connected to drive shafts 68, 69 respectively corresponding to the drive shafts I9, 20 of Fig. 1 and connected by sprockets 10', Hand a chain 12. The angular relation between the drive shaft 68, 69 may be varied by positioning of a frame 13 engaging the chain 12 and corresponding to the frame 46 of Fig. 1. The frame I3 together with the chain 12 and t1 .e sprockets 10, broadly constitute gear means for varying the angular relation between the'shafts 68, 69. Whereas in the arrangement of Fig. 1 the frame '13 is moved in response to changes of the mean pressure in the engine cylinder, in the arrangement of Fig. 2 such movement of the frame 13 is accomplished in response to changes of the fuel supply to the cylinder 65. Tothis end the frame 13 is connected to a stem I4 of a hydraulic motor 15 having a piston 16 connected to the stem Hi and to the right-hand end of a floating followup lever 11. The left-hand end of the lever TI is pivoted to a rod 18 for controlling the operation Of a fuel pump 19 corresponding to the pump 24 of Fig. 1. An intermediate point of the lever 11 is connected to a pilot valve 83 for controlling the supply of operating fluid under pressure to the hydraulic motor 15. With this arrangement upward movement of the rod 18 to increase the fuel supply causes clockwise turning movement of the lever 11 whereby the pilot valve 83 is moved upward and fluid under pressure is supplied to the upper side of the piston 16 and discharged from the lower side thereof,

resulting in downward movement of the piston to increase the supply of fluid under pressure to the lower side of the piston 16 and to discharge fiuid under pressure from the upper side thereof. resulting in upward movement of the piston 16 and the frame I3 to reduce the compression ratio of the engine. Upon movement of the piston 16 the pilot valve 83 is restored to its normal line in line position.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Internal combustion engine arrangement comprising cylinder means having a supply and an exhaust port, two pistons disposed in the cylinder means and forming a common compression space therewith, separate drive shafts connected to the pistons, gear means for connecting the drive shafts tomaintain certain angular relations between them, and means responsive to changes of the mean pressure in the cylinder means to vary the angular relation between the drive shafts and in order to reduce compression ratio with increasing mean pressure and vice versa.

2. Internal combustion engine arrangement comprising cylinder means having a supply and an exhaust port, two pistons disposed in the cylinder means and forming a common compression space therewith, means for supplying fuel ,to the compression space, separate drive shafts connected to the pistons, sprockets secured to the drive shafts and connected by chain means, and means responsive to changes of fuel supply cooperatively associated with the chain means to vary the angular relation between the drive shafts in order to reduce compression ratio with increased fuel supply and vice versa.

3. Internal combustion engine arrangement comprising a cylinder, two opposed pistons in the cylinder, separate drive shafts connected to the pistons, means including a pump actuated from one of the drive shafts for supplying fuel under pressure to the combustion spaced formed between the pistons, means for controlling the fuel supply separate sprockets secured to the drive shafts and a chain connecting the sprockets to maintain certain angular relations between the drive shafts, means cooperatively associated with the chain to vary the angular relation of the changes on the engine for controlling the last named means.

4. Internal combustion engine arrangement comprising a cylinder, two opposed pistons in the cylinder forming a combustion space between them, separate drive shafts connected to the pistons, means including a pump actuated from one of the drive shafts for supplying fuel under pressure to the combustion space, means for controlling the fuel supply, separate sprockets secured to the drive shafts and a chain connecting the sprockets to maintain certain angular relations between the drive shafts, means cooperatively associated with the chain to Vary the angular relation of the drive shafts, and a hydraulic motor having a pressure chamber communicating with the compression space to actuate the last named means in order to reduce the compression ratio with increasing load above a predetermined explosion pressure and vice versa.

5. Internal combustion engine 4 arrangement comprising a cylinder having a supply port and an exhaust port, opposed pistons movable in the cylinder and controlling said ports, separate drive shafts connected to the pistons, means for supplying fuel to the combustion chamber formed between the pistons comprising a reciprocating pump actuated from one of the drive shafts, means for controlling the pump to vary the fuel supply, gear means connecting the drive shafts to maintain certain angular relations between them, and means for controlling the gear means to vary the angular relation between the drive shafts in order to reduce the compression ratio in response to movement of the pump control means comprising a hydraulic motor having a piston connected to the gear means and a pilot valve for the motor connected to the pump control means.

6. Internal combustion engine arrangement according to claim 1 including a gas turbine having an inlet connected to the exhaust port, a blower driven by the gas turbine and connected to the supply port, separate generators driven from the drive shafts, an electric line connected to the generators, and an electric motor connected to the electric line for driving the blower during starting .and adapted to be driven by the gas turbine and operated as, a generator during normal operation.

'7. Internal combustion engine arrangement to the pistons, gear means for connecting the drive shafts to maintain certain angular relations between them, and means responsive to load changes on the engine to vary the angular relation between the drive shafts in order to reduce the compression ratio with increasing load and vice versa, electric generator means driven from the drive shafts; a motor connected to the gen' erator means, and a blower driven by the motor for supplying air under pressure to the supply drive shafts, and means responsive to load t,

Davin c. PRINCE. 

